The invention relates to a friction gear for a separate accessory unit in an internal combustion engine equipped with belt-driven auxiliary units, comprising a friction wheel in continuous or controlled drive connection with a drive wheel for the accessory unit, and a belt for a belt drive of the internal combustion engine which the friction wheel contacts or may be brought into contact therewith, whereby the friction wheel, which is held or controllable in/out of the drive connection via a swivel arm coupled on the engine side by means of a control device, is provided with a protective device which is connected to the swivel arm in parts.
Such a friction gear has been proposed in the unpublished German patent application 103 30 672, wherein the swivel arm shown in FIGS. 2 and 3 is designed as shown in the perspective view in FIG. 4 of another German patent application 103 09 061, namely, as a swivel arm having a bearing eye on which two guide levers which support the friction wheel are positioned. As shown in FIG. 2 of the above-cited P 103 30 672, a cover is associated with the guide lever farthest from the engine and is connected as a single piece to the protective housing covering the friction wheel on one side.